How Darwinism Stands To-Day 375 



The scepticism as to transmission of bodily modifications was 

 focussed by Sir Francis Galton and by Professor August Weis- 

 mann; and many would say that one of the great changes in 

 Darwinism since Darwin's day has been the abandonment of 

 belief in the Lamarckian postulate of the transmission of modifi- 

 cations. There are some difficult cases, however, which suggest 

 that biologists must not be in a hurry to shut out the possibility 

 of such transmission. Admitting a few difficult cases, we can 

 only record our impression that the available evidence indicating 

 a transmission of "acquired characters" as such or in any repre- 

 sentative degree is very inconclusive. But this would not be 

 admitted by such a distinguished zoologist as Professor E. W. 

 MacBride; and the scientific outlook should be that of an open 

 mind, associated with an eager search for more facts. 



Those who are unfamiliar with the subject often ask how 

 a race could make progress at all if acquired characters were not 

 transmitted from generation to generation. The answer is that 

 the changes which make for racial progress are variations and 

 mutations arising from within, from disturbances and rear- 

 rangements, permutations and combinations, in the germ-cells 

 from which new individuals arise. In 1796 the utmost speed of 

 the trotting horse was stated at a mile in 2 min. 37 sec.; in 1896 

 at 2 min. 10 sec. Does it not follow that the trotting horse has 

 been improved by the transmission of the results of the system- 

 atic training in trotting? It is certain that this conclusion does 

 not follow from the available evidence, which points to the con- 

 clusion that the improvement in speed has been mainly due to 

 the selective breeding of constitutionally swift horses. The 

 trotter is born, not made. 



It should also be understood that modifications may re- 

 appear, not because they have been transmitted, but because the 

 conditions which originally brought about the change may still 

 persist and produce the same effect on the offspring. And as to 

 the inheritance of disease, this is apparently confined to constitu- 



